Three-component, room temperature crotylation catalyzed by solid-supported Brønsted acid: enantioselective synthesis of homoallylic carbamates.

[reaction: see text] A heterogeneous, three-component crotylation of in situ generated N-acyl iminium ions has been developed. This reaction proceeds under ambient temperature in MeCN and is catalyzed by macroporous polystyrene-bound sulfonic acid (MP-TsOH). Workup is accomplished by filtration, upon which the catalyst is recoverable. A range of homoallylic amine equivalents have been prepared from the corresponding aldehydes, carbamates, and chiral (E)-crotylsilanes in a highly stereoselective manner.